Automatic correction device for gyroscopic compasses



y 2, 9 w. R. HIGHT ETAL 2,403,000

AUTOMATIC CORRECTION DEVICE FOR GYROSCOPIC COMPASSES Filed ke 50, 1937 s Sheets-Sheet 1 1 Il "ghh:

INVENTORS THEIR ATTORNEY July 2, 1946- w. R. HIGHT ETAL AUTOMATIC CORRECTION DEVICE FOR GYROSCOPIG COMPASSES s Sheerls-Sheet 2 Filed Nov. 30, 1937 'lllll'flllllllllllll INVENTORS (LUHM H. fi/GH 7% Rm 7 mm L Us Y R INQ\\K \k v-v E mm m n W 0 A M m m hm 5 M W m I mm July 2, 1946. w. R. HIGHT ETAL AUTOMATIC CORRECTION DEVICE FOR GYRO SCOPIG COMPASSES s Sheets-Sheet 3 Filed Nov. 50, 1.937

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11/101 4 llllllllll INVENTORS MLL/AM /?.h/GHT"\% LDMUNO fi. W/mruH/vs 483M THE/R Anew Patented AUTOMATIC CORRECTION DEVICE FOR GYROSCOPIC COMPASSES William R. Hlght, St. Albans, N. Y., and Bruno A.

Wittkulms, Summit, N. L, assign on to Sperry Gyroscope Company, Inc., Brooklyn, N. Y., a corporation of New York Application November 30, 1937, Serial No. 177,174

Claims. 1 This invention relates to automatic correction devices for gyroscopic compasses.

In this art it is well known that the Sperry gyroscopic compass deviates from the true north in accordance with the following equation:

aK cos H cos L D +b tan L compass by means of the so-called cosine ring,

while the present practice is to set in the speed and cosine L by hand settings graduated in accordance with the speed in knots and latitude of the ship.

The present invention relates to means for setting in speed automatically from the ships speed. While we are aware that this idea is not broadly new, it has never come into use in practice, probably because a hand setting for cosine L was still required at the compass. Preferably, we combine the ship's speed with cosine L in a device on the instrument panel, so that the only factor of the first element of the equation that is introduced at the compass is cosine H, which is also put in automatically.

Referring to the drawings, showing one form our invention may assume,

Fig. 1 is a part of a plan view of a portion of a gyroscopic compass showing the coarse and line compass cards, with the correction device in dotted lines.

Fig. 2 is a detailed sectional view through the portion of the correction device.

Fig. 3 is a diagrammatic view and partial wiring diagram of the means on the panel for transmitting the speed and latitude corrections to the compass.

Fig. 4 is a plan view of the latitude dial on the same.

Fig. 5 is a detail of the one-way drive between this device and the propeller shafts.

Fig. 6 is a vertical section through the course transmitter and the correction mechanism, taken substantially on line B-l of Fig. 1.

Fig. 'l is a cross section through the threedimensional cam 01' the correction device, approximately at the zero end of the cam.

Fig. 8 is a similar cross section taken through the other end of the cam.

While the speed of the ship may be obtained in many different ways, we have taken the speed of the propeller or propellers as representative of the ship's speed. The drawings are shown as representing a twin screw ship, in which case the average speed of the two screws l and I is used. To each propeller shaft we connect a transmitter 2, 2. preferably of the self-synchronous type. These transmitters actuate a double wound se1syn" differential 3 on the instrument panel which revolves the shaft 4 at a speed proportional to the average speed of the two propellers. Said shaft is connected through a oneway flexible drive '5 to shaft 8 to render the correction device inoperative when the propellers are reversed. Said drive is shown as comprising a disc I on shaft 4 having a pin 8 thereon which engages between the two end 9 of a coil spring 10. A second pin II on disc I! is driven by tension in the spring. The hub ii of said disc I2 is formed with a V-notch into which are yieldingly pressed the eccentric cams l4 and I4 which are pivoted on a second disc l8 on shaft 6 and spring pressed by curved springs ll, the outer ends of which are clamped to pins IS on disc l8. Referring to Fig. 5, it will be seen that counter-clockwise rotation of the hub l3 will cause the cams to lock and drive disc 18 with disc l2. direction, however, will release the cams and result in no drive being imparted to the disc It. This mechanism is to prevent reversing of the propellers from driving the correction device, the correction device being merely set to zero at that time. Since large vessels seldom travel backwards very far, this mechanism operates satisfacto'rily during all ordinary conditions.

Shaft 6 is shown as driving, through suitable gearing, a pinion H! which drives one arm of a three arm differential IS. The second or planetary arm 82 of said differential drives the shaft 20, as will be explained, proportionally to K cos L and therefore drives through gearing 2| a transmitter 2-3 which transmits the correction aK, cos L 23', on the shaft of which is shown a second Rotation of the hub in the opposite Y 3 worm 24 driving a worm wheel 2!, the latter turning an elongated pinion 2! which rotates a special three-dimensional cam 21 through gear Said cam is positioned longitudinally by means of the latitude setting knob 2|, which is turned until the latitude dial 2. shows the approximate latitude in which the ship is at the time. This operation positions cam 21 longitudinally by means of a pinion II on the cross shaft II, which pinion meshes with circular rack teeth I2 on a cylindrical extension from the cam.

The cam is so laid out that the lift of the pin I thereon for each latitude, which is represented by the length of the radius of the spirals in Figs. 7 and 8 beyond the dotted base circle, is proportional to the speed of the ship, and so that the angular distance through which the cam is rotated from the zero position to reach that lift is directly proportional to speed and inversely proportional to the cosine of the latitude the earth's speed is the greatest, and this effect increases with increasing latitude proportionally t The cross section of the right hand end of the cam. shown in Fig. 7, is laid out for zero latitude and if the ship is proceeding at 10 knots, the cam would be rotated until the pin lies over point P, i. e., the cam would be rotated through 54". If the ship, however, is in 70 latitude and proceeding at the same speed, the cam would be rotated through 126 (Fig. 8) so that the pin rests on point P for .the 10 knot speed, the radius being the same in the two cases, and all points of the cam between these two extremes are similarly laid out, the angular distance through which it is necessary to rotate the cam to reach this 10 knot speed varying from 54 to 126' in accordance with 1 cos L which moves longitudinally a rack bar 31 in proportion to the movements of the pin. Said bar radially positions a ball carriage 21' on a disc 38 which is driven at constant speed from a motor II, the position of the balls varying from the central position, at which the driven cylinder ll would stand still. to the maximum speed position at the lower edge of the disc 28, in which the cylinder 40 would be driven at maximum speed. The cylinder 40 therefore, in its total number of revolutions, integrates with respect to time the linear displacement of carriage 31. The cylinder ll is connected through suitable gearing ll and dear I toturn the third arm ll of the differential II, this mechanism now automatically differentiating the travel of the ship with respect to time. giving speed as a linear displacement of carriage ll.

A consideration of the mechanism will show that the radial position of the ball carriage l'l' on disc is will always represent in value the speed of the propeller shafts, since it is only this condition in which a condition of equilibrium is reached. In other words, if the primary arm ll of the diiferential is being driven faster than the follow-back arm ll of this differential driven by gear 42, rotation of shaft 20 would occur, which will readjust the position of the cam 21, and hence of pin iii and roller carriage 81', through worm gearing 22, 25 and pinion 28 until cylinder 40 is driven at the correct speed to reestablish the condition of equilibrium, in which gears II and 42 rotate at equal speeds and in opposite direction.

The cam is also so laid out as to take care of several variables, including the fact that the p' Speed d es not vary directly as the propeller speed, but in accordance with a known Iunctlon I other words,

4. L. cos L That is to say, the unknown of the mechanism appears as the rotation of the cam. The transmitter 23 will therefore be driven through a distance representing the desired correction to transmit to the gyro compass, the transmitter driving a repeater motor 45 connected to the correction device on the gyro compass in place of, or in addition to the standard setting knob for speed and latitude on the gyro compass.

The correction device shown is of the type shown in the prior patent to J. L, Chantemerle, #1,9l7,01'7, dated July 4, 1933, in which the combined latitude and speed correction is introduced through turning oi a single screw shaft I to position it in accordance with aK cos L and which positions a slider 41 sliding in upper and lower trackways 48, 48 in a pivotally mounted U-shaped member 19 pivoted on pins III. For hand setting. the knob 10 is turned until the proper speed curve on plate 1| intersects the proper latitude mark on vertical scale 12. Said Ushaped member is shown as having segmental gear teeth 5! thereon which mesh with similar teeth 52 in an arm is pivoted at 54, and the opposite end of which has a pin 55 engaging the cosine cam or eccentric ring 56 on the gyro compass. Since said ring only rotates to move pin 55, it may be said to be a two-dimensional cam as distinguished from the three-dimensional cam 21. Relative turning of the ship and compass will therefore rotate the arm 53. thus rotating the member 48 through a distance proportional to cosine H. The rotation of member 49 is transmitted to the gear sector 51 through the slider 41, said sector being pivoted on pins ll, thereby introducing the latitude and speed factors of the first member of the equation. The movement of the gear sector 51 is transmitted, respectively, to correct the effective position of the coarse and fine transmitters 59 and 60' on top of the gyro compass, the armature shafts ii of which are turned from the azimuth motor (not shown) in th gyro compass at 1:1 and 36:1 ratios, each transmitter shaft being provided, respectively, with a 360 compass card BI and a fine card 2, the latter graduated into ten equal sectors each representing 1. The correction device displaces the field of each transmitter proportionally to the correction required, the correction being of course, multiplied by a 36:1 ratio for the line transmitter and card by means of the step-up gearing 83, as compared to the reducing gearing 64 connecting sector 51 and the coarse transmitter.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having described our invention, what we claim and desire to secure by Letters Patent is:

1. In an automatic correction device for ships gyro compasses, a variable speed integrating device including a constantly driven disc, a roller carriage radially positioned thereon and a cylinder driven by said carriage, a three-arm differential device including one arm driven at a speed proportional to the ships speed, and a second arm driven by said cylinder, a follow back connection between the third arm of said differential and said roller carriage to radially position the latter, a computing mechanism in said connection, a latitude setting in said mechanism, whereby said third arm of said differential is positioned in accordance with the proper function of the speed and latitude of the ship, and means for connecting said third arm to said compass for correcting the latter.

2. In an automatic correction device for ships gyro compasses, a three-dimensional cam and cam pin, means for relatively positioning the same in one dimension in accordance with the latitude (L), automatic means for relatively positioning the same in another dimension so that the lift of the cam pin in the third dimension is proportional to the measured ships speed (K), said cam being so laid out that the required movement of said cam in said second dimension is proportional to K cos L and means for introducing the movement of said cam in said second dimension into said correction device.

3. In an automatic correction device for ships gyro compasses, a three part difierential device, means for driving one part thereof at a speed proportional to ships speed, a variable speed integrating device for driving another part of said device and having a linearly adjustable member to vary the output thereof, interconnecting means between the third part of said differential and said member to adjust the same so that the output of said integrator matches the ships speed, said interconnecting means including means for compensating for the effect of latitude on the correction, and transmitting means for positioning a part on said compass in accordance with the position of said third part of said differential device for correcting said compass.

4. In an automatic correction device for ships means for driving one part thereof at a speed proportional to ship; speed, a variable speed-integrating device for driving another part of said device and having a linearly adjustable member to vary the output thereof, interconnecting means between the third part of said differential and said member to adjust the same so that the output of said integrator matches the ships speed, whereby the distance moved by said member is proportional to the speed of the ship, and means connecting said third part of said differential to said compass for correcting the latter.

5. In an automatic correction device for ships gyro compasses, a, three-dimensional cam and cam pin, means for relatively positioning the same axially in accordance with the latitude (L), means for automatically deriving from the ship's movements its rate of speed, means for relatively positioning said cam rotationally so that the lift of the cam pin is proportional to said ships speed (K), said cam being so laid out that the required relative rotational movement of said cam is proportional to cos L and means for introducing said last named movement into said correction device.

6. In an automatic correction device for ships gyro compasses, a three-dimensional cam and cam pin unit, manual means for positioning the (parts of said unit in one dimension in accordance with the latitude (L), means for automatically positioning said parts in another dimension so that the lift of the cam pin is proportional to ships speed (K), said cam being so laid out that the required movement of said parts in said second dimension is proportional to K cos L i cos L and means for applying the resultant as a coursespeed-latitude correction to said compass.

7. In an automatic correction device for ships gyro compasses, means for determining the ships speed, a three-dimensional cam and cam pin, means for manually relatively positioning the same in one dimension in accordance with latitude (L), and speed integrating means for automatically relatively positioning the same in another dimension proportional to the ratio of the ships speed to the cosine of the latitude the correct value of said second positioning being reached when the lift of the cam pin becomes proportional to the continually and automatically introduced actual speed of the ship (K).

8. In an automatic correction device for ships gyro compasses, a three-dimensional cam and cam pin, means for relatively positioning the same in one dimension in accordance with the latitude (L), automatic means for relatively positioning the same in another dimension until the relative movement in the third dimension gyro compasses, a three part diiferential device, 78 matches the measured ships speed (K), said cam being so laid out that the required relative movement in saidsecond dimension is proportional to K cost and means for introducing said last named movement into said correction device.

9. In an automatic correction device for ships gyro compasses. a three-arm differential, one arm of which is rotated continuously at a speed proportional to the ship's speed (K), a variable speed device for rotating another arm including a constant speed driving member, a variable speed driven member and an adjustable intermediate member connecting said other members, the position of which is a measure or the speed at which the variable speed member is driven, a threedimensional cam and cam pin means, means for relatively positionin: said cam means in one dimension in accordance with the latitude (L), means connecting the third arm of said diflerential to position the cam means in a second dimension, the resultant movement of the cam means in the third dimension positioning said intermediate member, said cam means being so laid out that the required movement 01' the cam in the second dimension is proportional to cos L 8 10. In an automatic correction device for ships gyro compasses, a three-arm diflerential. one arm or which is rotated continuously at a speed proportional to the ship's speed (K), a variable speed device for rotating another arm including a constant speed driving member, a variabl speed driven member and an adjustable intermediate memand means for introducing the movement of said third arm into said correction device.

WILLIAM R. HIGHT. BRUNO A. WI'I'I'KUHNS. 

